The present invention relates to an inductively-coupled-plasma-processing apparatus used in the field of semiconductor processing. More specifically, the present invention relates to an inductively-coupled-plasma (ICP)-processing apparatus for subjecting a target substrate, such as a substrate for liquid crystal displays (LCD), i.e., an LCD glass substrate, to a process, such as deposition, etching, or the like, while using plasma. The term "semiconductor process" used herein includes various kinds of processes which are performed to manufacture a semiconductor device or a structure having wiring layers, electrodes, and the like to be connected to a semiconductor device, on a target substrate, such as a semiconductor wafer or an LCD (Liquid Crystal Display) substrate, by forming semiconductor layers, insulating layers, and conductive layers in predetermined patterns on the target substrate.
In a manufacturing process of a liquid crystal display (LCD), the surface of a rectangular glass-made LCD glass substrate is subjected to a process, such as deposition or etching. As an apparatus for executing this process using plasma, an inductively-coupled-plasma-processing apparatus capable of generating high-density plasma is known.
In a typical structure of the inductively-coupled-plasma-processing apparatus, a dielectric panel (window panel) is formed on the ceiling of an airtight process chamber, and a radio-frequency (RF) antenna is arranged above the dielectric panel. The RF antenna generates an inductive electric field in the process chamber and the field causes a process gas to be turned into plasma. Using this plasma, the substrate in the process chamber is subjected to a process such as deposition or etching.
Usually, target substrates (LCD glass substrates) to be processed in LCD manufacturing processes each have a size enough to obtain a plurality of LCD panel products, for example, nine LCD panel products, from one substrate. The sizes are therefore considerably greater than those of LCDs on the market. Recently the LCD glass substrates have been increased in size more and more in accordance with upsizing of LCDs themselves. For example, a 1-square-millimeter LCD glass substrate has appeared.
For the above reason, an inductively-coupled-plasma-processing apparatus for processing an LCD glass substrate increases in size, and so does a dielectric panel arranged between the LCD glass substrate and the RF antenna. The dielectric panel is thickened according to an increase in plan-view size so as to have strength enough to withstand a difference in pressure between the inside and outside of a process chamber and the dead weight thereof. If, however, the dielectric panel increases in thickness, the distance between the RF antenna and the process chamber increases, which causes a decrease in energy efficiency.
U.S. Pat. No. 5,589,737 discloses a structure for countering the above problem of the inductively-coupled-plasma-processing apparatus. In this structure, a main vessel is partitioned into an upper antenna chamber and a lower process chamber by means of a dielectric panel. A supporting frame having a plurality of rails, such as rails crossing each other at the center of the main vessel, is arranged in accordance with the partitioning position of the main vessel, and the dielectric panel is placed on the supporting frame. The dielectric panel comprises a plurality of segments corresponding to the rails of the supporting frame.
According to the structure of U.S. Pat. No. 5,589,737, the weight of the dielectric panel and the pressure difference between the inside and outside of the process chamber are all sustained finally by the outer section of the supporting frame extending along the inner surface of the main vessel. For this reason, the dielectric panel is still easy to bend downward in the central part, irrespective the presence of the rails of the supporting frame. In order to lessen this phenomenon, the entire supporting frame has to be sturdy; however, in this case, it increases in size and weight and causes an undesirable effect from the viewpoint of the profile in the process chamber, and the operability, maintenance and costs of the apparatus.